Cationic Prostaglandin Emulsion for Ocular Stability

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Solution Overview

Problem

Prostaglandins, such as latanoprost, are chemically unstable under light and heat, leading to hydrolysis and oxidation, which affects their stability and requires specific storage conditions, and existing emulsions often cause eye irritation due to high surfactant amounts.

Innovation Solution

A colloidal cationic oil-in-water emulsion with a prostaglandin, a saturated oil, and a low amount of cetalkonium chloride as a quaternary ammonium surfactant, maintaining a prostaglandin/surfactant ratio of 0.5 to 5, which enhances chemical stability and reduces surfactant-related eye irritation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If high amounts of surfactants are used in emulsions to stabilize prostaglandins, then the chemical stability of prostaglandins is improved, but eye irritation and itching increase

Engineering Contradiction:
Improvechemical stability of prostaglandinsVSAvoideye irritation
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the concentration parameter of surfactants from conventional high amounts to very low amounts (0.001-0.1% w/w), while adjusting the oil/surfactant ratio parameter to maintain emulsion stability. This parameter optimization resolves the contradiction by achieving stability with minimal surfactant content, reducing eye irritation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite emulsion system combining prostaglandin, saturated oil (iodine value ≤2), and quaternary ammonium compound in specific ratios. This composite formulation achieves stable prostaglandin stabilization through synergistic interaction of components, avoiding the need for high surfactant concentrations that cause irritation.

Inventive Principle:
Principle #40Composite materials

2Productivity

If light and heat are applied to prostaglandins, then the prostaglandins become more reactive, but chemical stability decreases due to hydrolysis and oxidation

Engineering Contradiction:
ImprovereactivityVSAvoidchemical stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent converts the harmful effect of light and heat into beneficial stabilization by using saturated oil (with low iodine value ≤2) as the emulsion medium. The saturated oil resists oxidation and hydrolysis caused by light and heat, creating a protective environment that preserves prostaglandin stability while maintaining necessary reactivity for therapeutic effect.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent creates an inert environment using saturated oil as the emulsion phase, which is resistant to oxidation and hydrolysis. This inert medium protects the prostaglandin from degradation by light and heat, maintaining chemical stability without requiring restrictive storage conditions.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

3Object-affected harmful factors

If very low amounts of surfactants are used in emulsions, then eye irritation is reduced, but emulsion stability may be compromised

Engineering Contradiction:
Improveeye irritationVSAvoidemulsion stability
Core Design Contradiction:
Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent optimizes the oil/surfactant ratio parameter to ranges of 50-500 (preferably 100-400), which maintains emulsion stability at very low surfactant concentrations. This parameter adjustment ensures that minimal surfactant content is sufficient for stable emulsion formation, resolving the contradiction between stability and irritation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses quaternary ammonium compounds (such as cetalkonium chloride) as cationic surfactants that replicate the stabilizing function of conventional surfactants with higher efficiency at lower concentrations. This allows achieving emulsion stability with reduced surfactant amounts, minimizing eye irritation.

Inventive Principle:
Principle #26Copying

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The emulsion achieves remarkable stability and tolerability, maintaining therapeutic effectiveness while minimizing ocular discomfort, with the prostaglandin/surfactant ratio ensuring enhanced chemical stability and reduced surfactant toxicity.

Implementation Method 1

one or more surfactants including one quaternary ammonium compound, which is cetalkonium chloride

Methodology Applied
Scientific EffectSurfactant: Surfactant

Implementation Method 2

an oil having a iodine value ≤ 2

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Implementation Method 3

these two elements (i.e. light and heat) may have an impact on the stability of latanoprost by provoking its hydrolyzation and/or oxidation

Methodology Applied
Scientific EffectHydrolysis resistance: Hydrolysis

Implementation Method 4

A colloidal cationic oil-in-water emulsion comprising: a prostaglandin, an oil having a iodine value ≤ 2, one or more surfactants

Methodology Applied
Scientific EffectColloidal stability: Colloid

Data Source

PatentEP2403477B8Cationic oil-in-water emulsions containing prostaglandins and uses thereof
Publication Date: 2014.02.26 SANTEN SAS

AI summary

The present invention relates to a colloidal cationic oil-in-water emulsion comprising: -a prostaglandin, -an oil having a iodine value = 2, -one or more surfactants including at least one quaternary ammonium compound, -water, wherein the prostaglandin/total sum of surfactants mass ratio is comprised between 0.5 and 5. The present invention also pertains to the use of said cationic oil-in- water emulsions for enhancing the stability of said prostaglandins, for the treatment of ocular hypertension and/or glaucoma, for promoting growth of eyelashes and/or for treating eyelash hypotrichosis.